Jerry McCrea/The Star-LedgerAn AirTrain makes its way from Newark Liberty Airport to the rail terminal right near Newark Liberty Airport in Newark.

NEWARK — The AirTrain at Newark Liberty International Airport shut down for several hours today due to a power failure, the Port Authority of New York and New Jersey said.

Service along most of the 3-mile elevated monorail system was restored at 1:10 p.m., after going out at 7 a.m., said Ron Marsico, a Port Authority spokesman. Marsico said a mile-long stretch linking the AirTrain system to a heavy rail station in Newark serving New Jersey Transit and Amtrak trains on the Northeast Corridor line was restored at 4:30 p.m. Shuttle buses filled in while AirTrain service was out.

Marsico said there were no reported injuries as a result of the outage. He said the cause of the outage was under investigation. The system’s manufacturer, Bombardier Transportation, has been called in to help. Marsico could not say whether any passengers were stranded inside the trains while the power was out, or whether the outage caused anyone to miss a flight.

The AirTrain system connects Newark Liberty’s three passenger terminals, four long-term parking lots, a rental car center, and Northeast Corridor trains. The sleek, automated AirTrain cars circulate the airport round the clock, providing more than 30,000 free rides a day, with a train arriving at each terminal every three minutes during peak hours.